Use of pigments as disperse dyestuffs

ABSTRACT

Use of pigments according to formula (I)                  
 
wherein all substituents have the meanings as defined in claim  1  for dyeing semisynthetic or synthetic hydrophobic fiber materials in aqueous media as well as semisynthetic or synthetic hydrophobic fiber materials dyed with such pigments.

The invention relates to the use of certain pigments as dispersedyestuffs.

The word “pigment” is of Latin origin (pigmentum) and originally denoteda color in the sense of a coloring matter, but was later extended toindicate colored decoration (e.g., makeup). In the late Middle Ages, theword was also used for all kinds of plant and vegetable extracts,especially those used for coloring. The word pigment is still used inthis sense in biological terminology; it is taken to mean dyestuffs ofplant or animal organisms that occur as very small grains inside thecells or cell membranes, as deposits in tissues, or suspended in bodyfluids.

The modern meaning associated with the word pigment originated in thiscentury. According to accepted standards (DIN 55943 and DIN 55945) theword pigment means a substance consisting of small particles that ispractically insoluble in the applied medium and is used on account ofits coloring, protective, or magnetic properties. Both pigments and dyesare included in the general term “coloring materials”, which denotes allmaterials used for their coloring properties. The characteristic thatdistinguishes pigments from soluble organic dyes is their low solubilityin solvents and binders. Pigments can be characterized by their chemicalcomposition, and by their optical or technical properties.

Pigments can be classified into two categories:

-   (i) inorganic pigments-   (ii) organic pigments

The most important areas of use of pigments are paints, varnishes,plastics, artists' colors, printing inks for paper and textiles, leatherdecoration, building materials (cement, renderings, concrete bricks andtiles—mostly based on iron oxide and chromium oxide pigments), leatherimitates, floor coverings, rubber, paper, cosmetics, ceramic glazes, andenamels.

The paint industry uses high-quality pigments almost exclusively. Anoptimal, uniform particle size is important because it influences gloss,hiding power, tinting strength, and lightening power. Paint films mustnot be too thick, therefore pigments with good tinting strength andhiding power combined with optimum dispersing properties are needed.

White pigments are used for white coloring and covering, but also forreducing (lightening) colored and black pigments. They must have aminimal intrinsic color tone.

When choosing a pigment for a particular application, several pointsnormally have to be considered. The coloring properties (e.g., color,tinting strength or lightening power, hiding power) are important indetermining application efficiency and hence economics. The followingproperties are also important:

-   1) General chemical and physical properties: chemical composition,    moisture and salt content, content of water-soluble and acid-soluble    matter, particle size, density, and hardness-   2) Stability properties: resistance toward light, weather, heat, and    chemicals, anti-corrosive properties, retention of gloss-   3) Behavior in binders: interaction with the binder properties,    dispersibility, special properties in certain binders,    compatibility, and solidifying effect.

Disperse dyes are colorants with low water solubility that, in theirdisperse colloidal form, are suitable for dyeing and printinghydrophobic fibers and fabrics.

Models for the dyeing of polyester fibers with disperse dyes have beendeveloped. When the dye is applied from aqueous medium, it is adsorbedfrom the molecularly dispersed aqueous solution onto the fiber surfaceand then diffuses into the interior of the fiber. The followingparameters determine the rate of dyeing and, to some extent, theleveling properties:

-   (1) the dissolution rate during the transition from the dispersed    crystalline state of the dye into the molecularly dispersed phase,    and-   (2) the diffusion rate at the fiber surface and, especially, in the    interior of the fiber.

The rates of both processes vary with temperature.

Differences in geometry and polarity of the dye molecules can lead towide variations in these finishing or dye-specific properties and canhave a marked effect on the absorption characteristics of all dyes,irrespective of whether single-component or combination dyeing processesare used. For instance, uneven dyeing may occur when an unequaldistribution of particle size results in insufficient dispersionstability and, thus, crystal growth and precipitation at the substratesurface.

Industrially applied disperse dyes are based on numerous chromophoresystems. Approximately 60% of all products are azo dyes and ca. 25% areanthraquinone dyes, with the remainder distributed among quinophthalone,methine, naphthalimide, naphthoquinone, and nitro dyes.

Surprisingly, it was found that certain pigments can be used for dyeingtextile fibers in aqueous media.

The invention relates to the use of pigments or mixtures of pigmentsaccording to formula (I)

wherein R₁–R₁₂ independently from each other signify H, halogen, —NO₂,—CN, —OH, —CH₃, —NH₂ or NHCH₃,in a dyeing process which takes place in aqueous media.

Preferably, pigments or mixtures of pigments are used wherein R₁–R₁₂independently from each other signify H, halogen or —CN.

More preferably, pigments or mixtures of pigments are used whereinR₁–R₁₂ independently from each other signify H, —Cl or —CN.

Especially preferred is a pigment of formula (I) wherein all R₁–R₁₂ areH.

According to the invention, the pigments of formula (I) are used fordyeing and printing semisynthetic and, preferably, synthetic hydrophobicfiber materials, especially textile materials. Textile materialsconsisting of blended fabrics containing such semisynthetic hydrophobicfiber materials can also be dyed or printed by means of the dyes of thisinvention.

Suitable semisynthetic textile materials are mainly cellulose-2½acetate, cellulose triacetate polyamides and high molecular weightpolyesters as well as mixtures thereof with cellulose.

Synthetic hydrophobic textile materials consist mainly of lineararomatic polyester, for example of those consisting of terephthalic acidand glycols, in particular ethylene glycol or condensate of terephthalicacid and 1,4-bis(hydroxymethyl)cyclohexane; of polycarbonates, e.g.those consisting of alpha,alpha-dimethyl-4,4′-dihydroxydiphenyl-methaneand phosgene, and of fibers based on polyvinyl chloride and polyamide.

The hydrophobic synthetic materials can be in the form of sheet-like orthread-like structures, and can be processed, for example, to yarns orwoven, knitted or looped textile fabrics. The pigments of formula (I)are also suitable for dyeing hydrophobic synthetic material in the formof micro fibers.

It is expedient to convert the pigments according to formula (I) beforeuse, into a dye formulation. This is done by milling the dye to anaverage particle size of 0.1 to 10 micron. Milling can be carried out inthe presence of dispersants. Typically, the dried pigment is milled witha dispersant, and thereafter dried under vacuum or by spray drying.Printing pastes and dyebaths can be prepared by adding water to theformulation so obtained.

The pigments according to formula (I) are applied to the textilematerials by known dyeing or printing methods, e.g. those described inFrench patent application No. 1445371.

Typically, polyester fiber materials are dyed from an aqueous dispersionby the exhaust process in the presence of customary anionic or non-ionicdispersants and in the presence or absence of customary swelling agents(carrier) in the temperature range from 65° C. to 140° C.

Cellulose-2½-acetate is preferably dyed at a temperature from 65° C. to85° C. and Cellulose triacetate at temperatures of up to 125° C.

The pigments according to formula (I) are suitable for dyeing by thethermosol process, for the exhaust and continues process and forprinting as for modern imaging processes, e.g. thermo-transfer printingor ink-jet printing.

The dyeings are carried out from an aqueous liquor by the exhaustprocess, and the liquor ratio can be chosen from a wide range, forexample from 1:4 to 1:100, preferably from 1:6 to 1:50.

The dyeing time is from 20 to 90 minutes, preferably from 30 to 80minutes.

The dye liquors can additionally comprise other additives, for exampledyeing auxiliaries, dispersants, wetting agents and antifoams.

The liquor may also comprise mineral acids, such as sulfuric acid orphosphoric acid, or conveniently also organic acids, for example formicacid or acetic acid and/or salts, such as ammonium acetate or sodiumsulfate. The acids mainly serve to adjust the pH of the dye liquorswhich is preferably in the range from 4 to 5.

The pigments are usually present in the dye liquors in the form of afine dispersion. Suitable dispersants for the preparation of thisdispersion are e.g. anionic dispersants, such as aromatic sulfonicacid/formaldehyde condensates, sulfonated creosol oil/formaldehydecondensates, lignin sulfonates or copolymers of acrylic acid derivates,preferably aromatic sulfonic acid/formaldehyde condensate or ligninsulfonated, or nonionic dispersants based on polyalkylene oxidesobtainable, for examples, by polyaddition reaction from ethylene oxideor propylene oxide. Further suitable dispersants are listed in U.S. Pat.No. 4,895,981 or U.S. Pat. No. 5,910,624.

The dyeings or printings thus obtained, have good all-round fastness;particularly noticeable are the thermo-migration fastness, lightfastness, thermo-fixation-, and pleating fastness, as well as theexcellent wet fastness.

The invention further relates to semisynthetic or, preferably, synthetichydrophobic fiber materials, which were dyed or printed with pigments offormula (I).

In the following examples, the parts and percentages are by weight. Thetemperatures are given in degrees Celsius.

APPLICATION EXAMPLE

17.5 parts of the pigment of the following formula (Ia)

with 32.5 parts of a commercial dispersing agent based on ligninsulphonates, and pulverized to a powder. 1.2 parts of this dyepreparation are added to 2000 parts of demineralized water of 70° C.,which contains 40 parts of ammonium sulfate; the pH value of the dyebath is set at 5 with 85% formic acid. 100 parts of washed polyesterfiber fabric are placed in this dye bath, the container is closed,heated to 130° C. over the course of 20 minutes, and dyeing continuesfor a further 60 minutes at this temperature. After cooling, thepolyester fiber fabric is removed from the dye bath, rinsed, soaped andcleansed by reduction with sodium hydrosulphite in the usual way. Afterthermo-fixation (180° C., 30 min), a brownish orange dyeing is obtainedwith very good all-round fastness, especially fastness to light andsublimation, in particular excellent wet fastness.

1. A process for dyeing a semisynthetic or synthetic hydrophobic fibermaterial comprising the steps of: providing at least one pigmentaccording to formula (I)

where R₁–R₁₂ independently from each other signify H, halogen, —NO₂,—CN, —OH, —CH₃, —NH₂ or NHCH₃, in an aqueous media; providing asemisynthetic or synthetic hydrophobic fiber material; and contactingsaid semisynthetic or synthetic hydrophobic fiber material with said atleast one pigment.
 2. The process for dyeing semisynthetic or synthetichydrophobic fiber material according to claim 1 where R₁–R₁₂independently from each other signify H, halogen or —CN.
 3. The processfor dyeing semisynthetic or synthetic hydrophobic fiber materialaccording to claim 1 where R₁–R₁₂ independently from each other signifyH, —Cl or —CN.
 4. The process for dyeing semisynthetic or synthetichydrophobic fiber material according to claim 1 where all R₁–R₁₂ are H.5. A process for the use of a pigment of formula (I)

where R₁–R₁₂ independently from each other is H, halogen, —NO₂, —CN,—OH, —CH₃, —NH₂ or NHCH₃, for dyeing polyester hydrophobic fibermaterial where the dyeing process takes place in an aqueous mediacomprising the step of contacting at least one pigment according toformula (I) in an aqueous media with semisynthetic or synthetichydrophobic fiber material.
 6. The process for the use of a pigmentaccording to claim 5 where R₁–R₁₂ independently from each other signifyH, halogen or —CN.
 7. The process for the use of a pigment according toclaim 5 where R₁–R₁₂ independently from each other signify H, —Cl or—CN.
 8. The process for the use of a pigment according to claim 5 whereall R₁–R₁₂ are H.